Get Tech Tips
Subscribe to free tech tips.
How I Failed to Re-diagnose: The Lesson I Learned
This is the tale of how I found myself stuck on a service call for over 12 hours on a weekend due to my failure to re-diagnose an issue. I was working for a service company that had many accounts with local gas stations. These were large customers, and we did everything we could to keep them happy.
One Friday, as I was gearing up for my on-call weekend, I was informed I must travel an hour and a half away early the next morning to a gas station where another technician had diagnosed a faulty X-13 blower motor. The technician didn’t have the right blower motor for the repair, so the system was still down. Here was the catch: no one knew what size blower motor was supposed to go in. No model numbers, no detailed notes, nothing. So, I grab every size aftermarket X-13 motor I could find in the shop. I had up to ¾ HP.
I arrived to find this location had two 5-ton package units mounted atop stands lifted 8 feet off the ground. After I set up the ladder and double-checked the motor size, I realized it was 1 HP. I began calling all the parts houses in the area, hoping someone answered at 8 am on a Saturday. No luck. I called parts houses in my local area and my co-workers to try and find a 1 HP X-13 motor that would work. Finally, I got in touch with one of my local suppliers. He had a motor that would fit the system I was working on, but he was an hour away from the supply house, and I was an additional hour and a half away. Luckily, my employer at the time picked it up for me, and I had the part within a couple of hours. I still had not re-diagnosed the system at that time.
Once I had the motor in hand, I quickly replaced it and had everything back together in a snap. I re-energized the system, and—I cursed loudly. The motor wouldn’t run. NOW I start re-diagnosing, a step I should have taken when I first arrived. As it turns out, the original motor was just fine. The motor was not receiving 24v to the motor module due to a faulty fan relay. I swapped out the 90-340 relay in the electrical compartment, restarted the system, and the blower ran beautifully. I hated myself.
I entertained the idea of packing up, walking away, and calling it complete, but I knew too well how that plays out. I began running complete system diagnostics and found the system charge to be very low. I started leak-searching the system with Big BluⓇ from Refrigeration Technologies and discovered a micro leak on the mechanical connection between the distributor tube and the TXV. No rubouts were apparent, and it wasn’t a super loose connection, but it was clearly leaking. This was a package unit, remember, so I had to recover the entire system charge before making any repairs.
Once recovered, I found out that the connection was just coming loose. A healthy dab of NylogⓇ on the fitting connection and a torque wrench was all I needed to pass a nitrogen pressure test. Of course, the repair process was time-consuming, but I eventually had the system evacuated, cleaned, recharged, and operating in peak condition under the current load.
I still would have needed to make the leak repair no matter what, but I could have easily saved 3.5 hours if I had re-diagnosed the system first when I arrived at the job. One could argue I was simply distracted by the chaos of the call, which would be true. However, a good technician should be able to follow the proper processes despite disorganization and frustration. I learned the importance of always checking behind yourself and others when you arrive to make a repair. Since then, I have found the real causes of issues previously diagnosed as bad TXVs, reversing valves, motors, etc. (either by another technician or me).
ALWAYS double-check your work and other people’s work. You never know how valuable it is until you fail to do it, and it costs you time and money.